RD3, the protein associated with Leber congenital amaurosis type 12, is required for guanylate cyclase trafficking in photoreceptor cells
Bibliographic record
Abstract
Guanylate cyclases, GC1 and GC2, are localized in the light-sensitive outer segment compartment of photoreceptor cells, where they play a crucial role in phototransduction by catalyzing the synthesis of cGMP, the second messenger of phototransduction, and regulating intracellular Ca(2+) levels in combination with the cGMP-gated channel. Mutations in GC1 are known to cause Leber congenital amaurosis type 1 (LCA1), a childhood disease associated with severe vision loss. Although the enzymatic and regulatory properties of guanylate cyclases have been studied extensively, the molecular determinants responsible for their trafficking in photoreceptors remain unknown. Here we show that RD3, a protein of unknown function encoded by a gene associated with photoreceptor degeneration in humans with Leber congenital amaurosis type 12 (LCA12), the rd3 mouse, and rcd2 collie, colocalizes and interacts with GC1 and GC2 in rod and cone photoreceptor cells of normal mice. GC1 and GC2 are undetectable in photoreceptors of the rd3 mouse deficient in RD3 by immunofluorescence microscopy. Cell expression studies show that RD3 mediates the export of GC1 from the endoplasmic reticulum to endosomal vesicles, and that the C terminus of GC1 is required for RD3 binding. Our results indicate that photoreceptor degeneration in the rd3 mouse, rcd2 dog, and LCA12 patients is caused by impaired RD3-mediated guanylate cyclase expression and trafficking. The resulting deficiency in cGMP synthesis and the constitutive closure of cGMP-gated channels might cause a reduction in intracellular Ca(2+) to a level below that required for long-term photoreceptor cell survival.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".